Anti-restriking oil circuit breaker having an anti-cavitation device



Jam 1967 A w. ROTH ETAL- 3,300,610

ANTI-RESTRIKfNG OIL CIRCUIT BREAKER HAVING AN ANTI-CAVITATION DEVICEFiled June 15, 1961 I 5 Sheets-Sheet 1 9 v INSULATING MATERIAL Fig.1

M/VEWEKS g 2 40m wseA/se Km ALE/EFT CATELLA 5 Sheets-Sheet 2 Z mf WK m Mm A ALBEET a4 T'LLA 6 51557 A/MOUD INSULATING MATERIAL Jan. 24, 1967 A.w. ROTH ETAL ANTI-RESTRIKING OIL CIRCUIT BREAKER HAVING ANANTI-CAVITATION DEVICE Flled June 15, 1961 LAMINATED MAGNETIC CORE Jan.24, 1967 A. w. ROTH ETAL 3,300,610

ANTI-RESTRIKING OIL CIRCUIT BREAKER HAVING AN ANTI-CAVITATION DEVICEFiled June 15, 1961 5 Sheets-Sheet :5

INVENTORS. ADRIEN WERNER ROTH ALBERT CATELLA ILBERT NICOUD United StatesPatent Ofiice 3,300,610 ANTI-RESTRIKING OIL CIRCUET BREAKER HAV- ING ANANTl-CAVITATION DEVICE Adrien W. Roth, Aarau, Switzerland, and AlbertCatella and Gilbert Nicoud, Lyon, France, assignors to CompagnieGenerale dElectricite, Paris, France, a corporation of France Filed June15, 1961, Ser. No. 117,363 Claims priority, application France, June 21,1960, 830,668 21 Claims. (Cl. 200150) The present invention relates to acircuit breaker and more particularly to a high-voltage, smalloil-volume circuit breaker provided with anti-restriking means and witha control mechanism controlling the opening speed of the circuit breakerto permit proper operation thereof irrespective of the nature of theoverload causing actuation of the circuit breaker.

It has been frequently proposed, for purposes of suppressing therestrikings after the interruption of capacitive currents by means ofthe circuit breakers having a small volume of oil, to blow oil into thespace in which the arc is produced, in order to accelerate theregeneration of the dielectric strength between the contacts after anatural passage of the current through zero. Such forced blowing orblast has as its effect to chase the ionized material out of the spacebetween the contacts and to replace the same by non-ionized material.

It is also known that if, within the first half-period which follows theseparation of the contacts of the circuit breaker, the opening distanceattains a suificient value, then the interruption without restrikingfinds itself favored; to obtain such result it has been customary in theprior art either to break up the circuit breaker into a great number ofinterrupting chambers or to impart to the movable rod of eachinterrupting chamber a very high speed from the moment of separation ofthe contacts and consequently to impart thereto a very highacceleration, prior to the separation. In the presence of thecomplication and difficulties of realization which seem to resulttherefrom, it has always :been recommended to date to seek theinterruption without re-striking by means of a powerful forced blast,whereas a slight augmentation in the rapidity of increase of the openinginterval has been indicated only as auxiliary means to favor thedielectric regeneration.

However, the forced blast, in addition to requiring the use ofrelatively powerful pumps and leading to a rather complicatedinstallation, presents the inconvenience of increasing the over-voltagesor voltage surges with the interruption of small inductive currents; ineffect, in the case of small inductive currents, and contrary to thatwhich takes place in the case of capacitive currents, the voltage surgesare caused by the brutal cancellation or draw-out of the current priorto its natural passage through zero, and the forced blast multiplies, toa very high proportion, the current draw-out capacity by the circuitbreaker; the forced blast, therefore, finds itself at the origin ofvoltage surges of which the amplitude can be reduced only by the use ofauxiliary damping resistances. These auxiliary resistances and theauxiliary interrupters which such prior art circuit breakersnecessitate, complicate the construction and the operation thereof sothat an effort is made with conventional circuit breakers including suchauxiliary devices to limit the use thereof to very special cases inwhich the structure of the network renders the same indispensable.However, as a general rule, the adoption of the forced blast, therefore,entrains very definitely a significant complication with respect to theconventional circuit breaker.

33%,6 1 ll Patented Jan. 24, 1967 Consequently, according to the priorart teachings, there existed a dilemma confronting the designer ofcircuit breakers, namely either renounce the suppression of restrikingsin the interruption of capacitive currents, or employ the forced :blastwith its inevitable accompaniment of complications.

To escape from this dilemma, the present invention, avoiding recourse tothe forced blast, has turned to opening speeds much higher than thoserealized to date and proposes means to obtain this high speed while atthe same time avoiding the inconveniences which could result from thishigh speed such as causing a phenomenon of cavitation behind the movablecontact.

The present invention has as its object a high voltage circuit breakerwith a small oil volume in which, in the position of closure, the rod ofthe movable contact and the fixed contact fingers are disposed on theinside of an oil-injection pot closed by a spark-arrester covercharacterized in that, toward the end of closure of the circuit breaker,the rod of the movable contact has its movement damped by the armingforce which it exerts on an energy accumulator or energy storage device,which at the beginning of opening imparts a very high speed to themovable contact and injects over the same a current of anti-cavitationoil during the entire duration of possible restrikings in case ofcapacitive interruption.

Accordingly, it is an object of the present invention to provide acircuit breaker of the type mentioned hereinabove which effectivelyeliminates the drawbacks and shortcomings of the prior art constructionin a simple and effective manner.

It is another object of the present invention to provide a circuitbreaker of the type mentioned hereinabove which is reliable in operationwith all types of overloads, i.e., which is operative to interruptcapacitive currents as well as small inductive currents.

Still another object of the present invention resides in the provisionof a circuit breaker of universal applicability insofar as theinterrupted current is concerned which is relatively inexpensive andwhich achieves such versatility by simple and inexpensive means.

Still a further object of the present invention resides in the provisionof a circuit breaker utilizing a high open: ing speed to achieve thepurposes and functions described hereinabove.

Another object of the present invention resides in the provision of acircuit breaker of the type mentioned hereinabove which utilizes acavitation-compensating means to compensate for the cavitational effectsproduced by the high opening speeds used in the circuit breaker withoutthe disadvantages normally encountered with oil blasts or the like.

A further object of the present invention resides in the provision of acircuit breaker which obviates the need for forced blasts to regeneratethe dielectric strength in the space behind the contact.

Still a further object of the present invention resides in the provisionof a circuit breaker operative to interrupt not only capacitive currentsbut also small inductive currents without the side effects of voltagesurges and without the need of auxiliary damping resistances.

Still another object of the present invention resides in the provisionof a circuit breaker operative to effectively interrupt, not only shortcircuit currents and capacitive currents, but also small indicativecurrents without the necessity of complicated constructional details andcomplex operational aspects.

These and further objects, features and advantages of the presentinvention will become more obvious from the following description whentaken in connection with the accompanying drawing which shows, forpurposes of illustration only, one embodiment in accordance with thepresent invention, and wherein FIGURE 1 is an elevational crosssectional view through an anticavitation device in accordance with thepresent invention mounted on the fixed contact structure of the circuitbreaker.

FIGURE 2 is a cross sectional view taken along line IIII of FIGURE 1,and

FIGURE 3 is a schematic diagram of a circuit breaker and controlmechanism according to the present invention provided with meansnecessary to produce, .at the opportune moment, a slow down of theopening speed of the rod of the movable contact.

FIG. 4 is a diagram showing contact movement plotted against time.

FIG. 5 is an illustration of a conventional circuit breaker arrangementhaving a plurality of interrupting chambers connected in series.

From what will follow hereinafter, the term opening speed is to beinterpreted as the product of the speed of the rod of the interruptingchamber by the number of interrupting chambers, it being understood thatthe present invention relates to circuit breakers with a very highopening speed regardless of whether this opening high speed is obtainedonly by the increase of speed of the rod or also by that of the numberof interruptions.

The displacement at high speed of the contact rod within the oilproduces a cavitation behind the contact that is within the spaceionized by the arc; however, the empty space is a bad dielectric andthere is need to compensate for this cavitation by a supply of oil insuch a manner that at each instant, in spite of the speed, the state ofthe space between the contacts is substantially the same as if the speedwere zero. It is in that connection that intervenes the anti-cavitationdevice provided by the present invention. The anti-cavitation devicewhich causes the oil to penetarte through orifices into the spacesubjected to cavitation is regulated in such a manner as to compensateessentially for this'cavitation without producing eddying or swirls;such eddying or swirls would constitute in effect a forced blast whichis the source of the shortcomings mentioned hereinabove. Theanti-cavitation device provided by the present invention, additionally,offers certain advantages which will result from the description thatwill follow.

The high speed of the rod is also favorable to the interruption of ashort-circuit currents. Referring to FIGURE 4, this figure represents adiagram in which time is plotted along the abscissa and the distances oftravel of the movable contact member 12 are plotted along the ordinate.

In FIGURE 4, the curve a represents the diagram of the time to thefrequency of the network into which the circuit breaker is installed.

Line b intersecting the curve 1 at point M rep-resents the position of amovable contact member 12 in the position illustrated in FIGURE 1 inwhich it abuts abainst the tubular member 2.

Lince c intersecting the curve It at point N indicates the distancetraversed and time elapsed from the position of movable contact 12 inthe armed condition of the circuit breaker to the instance when thecontacts 12, 1 of the circuit breaker separate.

Line d indicates the position of the movable contact 12 for which theinterruption of the capacitive current is terminated with certainty, themovable contact 12 having traversed a distance d from th ep-osition N atthe moment of separation of the movable and fixed contacts 12, 1. Line ewhich intersects the curve 1 in point 0 corresponds to the position ofthe movable contact 12 for which the interruption of the short-circuitcurrent becomes possible, the movable contact 12 having traversed adistance oi for the moment of separation of the contacts 12, 1represented by line c, with a lapsed of time equal to t Line whichintersects curve 1 in point P corresponds to the position normallyattained by the movable part 12 a period of the frequency cycle after ithas attained the position :1 the distance traversed by the movablecontact 12 since the separation of the contacts 12, 1 now amounting to dand the time elapsed being equal to The time t corresponds to a passagethrough zero of the current of interruption-different from the curve awhich does not rep-resent the current of interruption but only a timediagram independent of the current of interruptionwhich takes passagethrough zero place between the positions d and d The movable contact 12,reaching the distance d at time t is represented by the point 0.However, the interruption of the current would be effectively producedonly at the time of either the first or the second passage of thecurrent through zero after the time t If T is the period of thealternating current, such passage through zero will necessarily occur ata moment 1 comprised between t and t -i-T, T being equal to 0.02 secondin the case of a fifty cycles per second alternating current and 0.0167second in the case of a sixty cycles per second alternating current. IfV is the speed of the movable contact 12, the position of the movablecontact at the moment of the interruption of the current will becomprised between the representative points 0 and P, the lattercorresponding to a distance equal d =d '+T-V from the position of theseparation of the contacts 1, 12 at point N corresponding to line 0.

If the speed of the movable contact 12 is, as presupposed, very high,then the distance d is much greater than d whereby the energy realizedby the arc in the course of the interruption at the distance d may bevery high, the energy related by the arc in the course of theinterruption at the distance d may be very great which renders moredifficult the construction of the circuit breaker. However, the circuitbreaker according to the present invention does not entail thisinconvenience, for it is actuated in such a manner that the speed of therod, very high at the moment of the separation of the contacts, isbrought back to a value much smaller prior to attaining the distance dIn accordance to one embodiment of the present invention, the slow-downor deceleration mechanism of the rod is actuated in a manner so as toact only in case of a short-circuit interruption, and in these cases itmay from the beginning of the movement of the rod, limit the speed to amaximum desired value; it has to be simply controlled by a currentmeasuring device within the phase considered which, above a certaincurrent threshold,

which is defined without great precision commands or orders the speedlimitation. Eventually, such a device may be situated within thegrounded control, at the base of the circuit breaker, and in that caseis controlled by the intensity transformer associated with theconsidered phase.

According to a modified embodiment of the present invention, the speedlimitation is obtained With each operation, and intervenes between thedistance d for which the interruption of the capacitive current isterminated with certainty and the distance d for which the interruptionof short-circuit currents becomes possible; the speed limitation actsthen also for the interruption of small inductive currents which isfavorable, for a high speed might favor the current draw-out.

Additionally, the present invention has as its further object theprovision of means intended to realize the high opening speed whichconstitutes one of the basic concepts of the present invention.According to a further feature of the present invention, the circuitbreaker pole, i.e., the pole members belonging to the same phase, may beconstituted in certain embodiments by placing in series interruptingchambers in which the speed of the rod is of the same order of magnitudeas thespeeds realized in conventional circuit breakers, and it will thencomprise a number of interrupting chambers which is clearly moreconsiderable than that of the circuit breakers of analogous voltage withsmall oil-volume realized to date, and this is still another feature ofthe present invention.

FIGURE 5 illustrates a conventional arrangement of interrupting chambersconnected in series, wherein 41, 42, 43 and 44 designate interruptingchambers similar to that of FIG. 3, the interrupting chamber beingmounted on insulators 45 and 46 and actuated by hydraulic jacks 47 and48.

According to still another feature of the present invention, the numberof chambers in series is, in a modified embodiment of the presentinvention, of the same order as that encountered in certain conventionalcircuit breakers, and, the very considerable acceleration which then hasto be imparted to the rod of each chamber to obtain, for the moment ofseparation of the contacts, the speed necessary for the interruption ofcapactive currents, is obtained by the release of the pneumatic controlenergy; the opening of the circuit breaker by pneumatic energy with aview to attain a very high speed in the separation of the contacts, andassociated, within a circuit breaker of small oil volume, with theanti-cavitation device mentioned hereinabove, constitutes also a featureof the invention.

As an illustrative embodiment, there may be used the hydropneumaticopening control, described in the French Patent No. 1,203,632, filedMarch 21, 1958, in the name of the assignee of the present applicationand in the three certificates of addition filed, respectively, on June6, 1958, November 3, 1959, and February 19, 1960, for Method ofHydro-Pneumatic Control for Electrical Apparatus and Application to aCircuit Breaker.

Neither the construction of a circuit breaker with a large number ofinterrupting chambers nor the opening control by means of pneumaticenergy, however, will be described herein since any conventional knownstructure may be used therefor. The present text will be limited to thedescription, non-limitative in nature, of a cavitation compensatingdevice according to the present invention, and to a circuit breakerequipped with such a device and provided with means, known per se, toassure to the opening the braking of the movable contact at an opportunetime.

Referring now to the drawing wherein like reference numerals are usedthroughout the various views to designate corresponding parts, and moreparticularly to FIG- URE l, the tubular member 2 secured to a piston 3slides along the axis of a cylindrical member 4. The piston 3 isdisplaced within the cylindrical member 4 in the lower part of which arearranged the fixed contacts 1 of any suitable construction of which onlya single one is shown in the drawing, A spring 5 normally urges thepiston member 3 downwardly as viewed in FIGURE 1, and thereby forces theoil located within the space 6 to pass through the throttling apertures7 of any suitable 1 cross section and inclined with respect to the axisof rod 2 so as to be divergent in the opening direction of rod 2. Thelower guide portion 8 re-directs the oil towards the contacts 1 andtoward the orifice of the spark arrester cover 9; as shown in crosssection in FIGURE 2, the spark arrestor cover comprises radial notches10. This arrangement enables a reduction in the play between thecylindrical bore 11 of the cover 9 and the movable rod 12 which, offersthe advantage of avoiding the premature extinction of the are which isthe cause of re-ignitions and sometimes re-strikings before the movablerod 12 has left the cover 9 and to permit to bring up to speed theanti-cavitation compensating device from the beginning of the movementof the disengagement of the movable contact, by assuring to the oil asufiicient passage cross section by means of the notches 10.

OPERATION The operation of the device illustrated in FIGURES 1 and 2 isas follows:

During closure of the circuit breaker, the compensating device is armedby the contact rod 12 which pushes the tubular member 2 and the piston 3upwardly during that time and compresses thereby the spring 5 whilepenetrating into the fixed contact.

During the disengagement, a portion of the energy of the spring 5 isadded to that of the conventional disengaging springs or of thehydro-pneumatic control of known construction to accelerate the rod 2and the rod 12 at the beginning of the opening movement when a highspeed is necessary; and the spring 5, pushing the piston 3, also forcesthe oil from space 6 through the apertures 7 against the guide 8 towardthe extremity of the contact rod 12 thereby suppressing the cavitationand increasing the dielectric strength. The time of operation of theanti-cavitation device is controlled by the diaphragm or throttlingapertures 7 in such a manner that the dielectric strength of theinterruption distance attains approximately 2 /2 times the peak value ofthe simple voltage, a half period after the movable rod leaves the sparkarrester cover 9 by eliminating the restrikings in case of capacitiveinterruptions. This forced flow of the oil ceases less than a halfperiod later, and the interruption of inductive currents will takeplace, after this position, under the action of only the auto-blast,within the zone in which the dielectric strength of the interruptiondistance maintains substantially the value indicated hereinabove.

As soon as the anti-cavitation device ceases its effect, the movablecontact may be braked very strongly and slowed down in order to reducethe energy released by the interruption of short-circuit currents, inthe most unfavorable case, that is when a passage through zeroaccidentally arrives for an opening very slightly smaller than theminimum opening necessary for the interruption, which entrains themaintenance of the are for a supplementary half period.

FIGURE 3 shows, in particularg a braking device for the movable contact12 which is operative by acting on the flow through an oil outlet ordischarge line 20 connected to a cylinder containing the actuatingpiston 16 of which the piston rod is connected by the transmissionlinkage 15 to the movable contact rod 12 which is displaced Within theinterrupting chamber 13 contained within the insulating envelope 14 ofthe circuit breaker. As soon as the current attains a value at which itbecomes desirable to slow down the movable part, the intensity ofcurrent traversing the circuit breaker which flows through the winding17 and acts in opposition to the traction spring 19 normally seeking tobring back the magnetic core 18 to the left, displaces the latter towardthe right, and the extremity 24 of the rod of piston 16, acting on thelever 25, tilts or rocks the lever 26 and displaces the check-value ball27 by the intermediary of the movable valve stem and spool portion 28.

The oil coming from the input line 21 passes through line 29 and theorifice of the ball 27, and acting in opposition to springs 30 and 31,displaces the pistons 32 and 33 toward the right as viewed in FIGURE -3,the line 34 being connected to the tank or sump. The displaced oil,passing through line 20 is throttled -by the channels 36 and 37 beforereaching the return line 23. This reduction in the useful cross sectionof the oil discharge eifectively brakes the movement of the piston 16.Thereafter, the lever 25 escapes from the free end 24 of the rod of thepiston 16, whereupon the check valve 27 is displacd toward the left andcuts off the connection with the oil supply 21, 29. As a result thereof,the pistons 32 and 33 are displaced toward the left under the action ofthe springs 30 and 31 and re-establish the direct dischargecommunication between lines 20 and 23, thereby permitting anew a rapidmovement of the movable contact toward the end of the path.

The operation of the valve 22 is regulated by conventional means in sucha manner as to avoid any appreciable oscillatory movements of themovable part.

The present invention offers the following advantages:

(a) Elimination of the phenomenon of cavitation at the extremity of themovable contact which could be caused by the high speed of the latter,by displacing oil in the direction of displacement of the contact.

The combined action of high speed and over-pressure due to the blowingaction eliminates the phenomena of cavitation as well as the formationof a conductive gas bubble producing restrikings in case of interruptionof capacitive currents.

'(b) There is avoided an appreciable elevation of the level of thevoltage surges in the interruption of weak inductive currents bylimiting the amplitude of the displacement of the oil by means of athrottling and by reducing the duration thereof to a time of the orderof the period, while the interrupter is constructed in such a mannerthat the interruption of magnetizing currents then takes place somehalf-periods after the end of the displacement of the oil, under theaction of the normal auto-blowing action of such apparatus whichcorresponds to the most favorable conditions of limiting voltage surges.The limitation of the duration presents, more-over, the advantage ofdecreasing the mechanical energy necessary to produce the blowing.

The device according to the present invention renders unnecessary theemployment of damping resistances for the voltage surges since theinterrupters with forced autoblast cause, in the interruption of smallinductive currents, only relatively small over-voltages or voltagesurges.

(c) The eventual use of the hydro-pneumatic control permits to obtain,for a reduced price and volume, a large energy and therewith a highacceleration with a high speed of the movable contact and satisfactorydamping.

(d) The initial high speed of the movable contact reduces the timenecessary to attain the optimum interrupting position of inductivecurrents and consequently the interrupting times of all types ofcurrents and the released energy.

(e) The eventual braking of the movable contact reduces the voltage ofthe arc, the released energy, the pressures developed within theinterrupting members and consequently the cost of the construction ofthe extinguishing chamber.

(f) The interruption of the action of the spring within theanti-cavitation device before the slow down of the movable contactfacilitates the latter operation and the braking in the course of thedisengagement reduces considerably the importance of the dampingnecessary at the end of the path.

-(g) The device utilized for the engagement permits to conserve a highspeed of the movable contact during the existence of the are at theclosure and to introduce only toward the end of the path a resistingforce which facilitates damping of the movable rod.

While we have shown and described one embodiment in accordance with thepresent invention, it is understood that the same is not limited theretobut is susceptible of many changes and modifications, and we thereforedo not wish to 'be limited to the details shown and described herein butintend to cover all changes and modifications encompassed by the scopeof the appended claims.

We claim:

1. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and the fixed contact fingers ofsaid stationary contact means being disposed on the inside of said oilinjection pot in the closing position thereof, and control means withinsaid oil injection pot for controlling the opening movement of saidmovhigh speed to said movable contact means and injecting on saidmovable contact means an anti-cavitation oil current in the direction ofmovement of said movable contact means substantially free of swirlingmovements during substantially the entire duration of possiblerestriking with capacitive interruptions.

2. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and the fixed contact fingers ofsaid stationary contact means being disposed on the inside of said oilinjection pot in the closing position thereof, and control means withinsaid oil injection pot for controlling the opening movement of saidmovable contact means including means for assisting in imparting at thebeginning of the opening movement a very high speed to said movablecontact means and means for injecting i011 said movable contact means ananti-cavitation oil current substantially in the direction of movementof said movable contact means during substantially the entire durationof possible restriking with capacitive interruptions, said control meansbeing regulated in such a manner that the maximum efficacy of saidanti-cavitation oil current commences less than a half-period after saidmovable contact means leaves said spark-arrested cover means andterminates at the maximum one period after said movable contact meansleaves said cover means.

3. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, actuating meansfor effecting opening of said circuit breaker, housing means effectivelyforming an oil injection pot and including spark-arrester cover means,said movable contact means and the fixed contact fingers of saidstationary contact means being disposed on the inside of said oilinjection pot in the closing position thereof, and control means withinsaid oil injection pot for controlling the opening movement of saidmovable contact means including energy storage means armedduring closuremovement of said movable contact means, and means including said energystorage means assisted by the force produced by said actuating means foraiding in imparting at the beginning of the opening movement a very highspeed to said movable contact means, and means for injecting on saidmovable contact means an anti-cavitation oil current substantially inthe direction of movement of said movable contact means during theentire duration of possible restriking wit-h capacitive interruptions.

4. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, actuating meansfor effecting opening of said circuit breaker, housing means effectivelyforming an oil injection pot and including spark-arrester cover means,said movable contact means and the fixed contact fingers of saidstationary contact means being disposed on the inside of said oilinjection pot in the closing position thereof, and control means withinsaid oil injection pot for controlling the opening movement of saidmovable contact means including energy storage means having disengagingspring means armed during closure movement of said movable contactmeans, and means including said energy storage means assisted by theforce produced by said actuating means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, and means for injecting on said movable contact means ananti-cavitation oil current substantially in the direction of openingmovement of said movable contact means during the entire duration ofpossibl restriking with capacitive interruptions.

5. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, actuating meansincluding a hydropneumatic control system for effecting opening of saidcircuit breaker, housing means eflectively forming an oil injection potand including spark-arrester cover means, said movable contact means andthe fixed contact fingers of said stationary contact means beingdisposed on the inside of said oil injection pot in the closing positionthereof, and control means Within said oil injection pot for controllingthe opening movement of said movable contact means including energystorage means armed during closure movement of said movable contactmeans, and means including said energy storage means assisted by theforce produced by said hydro-pneumatic control system of the actuatingmeans for aiding in imparting at the beginning of the opening movement avery high speed to said movable contact means, and means for injectingon said movable contact means an anti-cavitation oil currentsubstantially in the direction of opening movement of said movablecontact means during the entire duration of possible restriking withcapacitive interruptions.

6. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, housing meanseflectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and the fixed contact fingers ofsaid stationary contact means being disposed on the inside of said oilinjection pot in the closure position thereof, and control means Withinsaid oil injection pot for controlling the opening movement of saidmovable contact means including means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means and injecting on said movable contact means ananti-cavitation oil current in the direction of movement of said movablecontact means substantially free of swirling movements during the entireduration of possible restriking with capacitive interruption, theinterruption speed per pole structure being eflectively multiplied bymeans producing a plurality of interrupting points placed in series.

7. A high-voltage circuit breaker provided with cooperating stationaryand movable contact means, comprising means for imparting to saidmovable contact means a relatively very high opening velocity includingbraking means for subjecting said movable contact means to a brakingaction within a zone corresponding to substantially optimum positionthereof for interrupting short-circuit currents and small inductivecurrents, and means injecting on said movable contact means ananti-cavitation oil current substantially in the direction of openingmovement of said movable contact means and substantially during theentire duration of possible restriking with capacitive interruptions.

8. A high-voltage circuit breaker provided with cooperating stationaryand movable contact means, comprising means for imparting to saidmovable contact means a relatively very high opening velocity includingbraking means for subjecting said movable contact means to a brakingaction within a zone corresponding to substantially optimum positionthereof for interrupting short-circuit currents and small inductivecurrents, and means injecting on said movable contact means ananti-cavitation oil current substantially in the direction of openingmovement of said movable contact means and substantially during theentire duration of possible restriking with capacitive interruptions,said braking means including a fluid-controlled system having valvemeans and electromagnetic actuating means for actuating said valve meansin response to the current flowing through said circuitbreaker exceedinga predetermined threshold value to thereby control the flow of fluidmedium within said fluid system.

9. A high-voltage circuit breaker provided with cooperating stationaryand movable contact means, comprising means for imparting to saidmovable contact means a relatively very high opening velocity includingbraking means for subjecting said movable contact means to a brakingaction within a zone corresponding to substantially optimum positionthereof for interrupting short-circuit currents and small inductivcurrents, and means injecting on said movable contact means ananti-cavitation oil current substantially in the direction of openingmove ment of said movable contact means and substantially during theentire duration of possible restriking with capacitive interruptions,said braking means including a fluid-controlled system having valvemeans and electromagnetic actuating means for actuating said valve meansin response to the current flowing through said circuitbreaker exceedinga predetermined threshold value to thereby control the flow of fluidmedium within said fluid system, said braking means being operative byevacuation of said fluid medium.

lit. A high-voltage circuit breaker provided, within a housing, withcooperating stationary and movable contact means, comprising means forimparting to said movable contact means a relatively very high openingvelocity including braking means for subjecting said movable contactmeans to a braking action within a zone corresponding to substantiallyoptimum position thereof for interrupting short-circuit currents andsmall inductive currents, and means within said housing injecting onsaid movable contact means an anti-cavitation oil current in thedirection of opening movement of said movable contact means andsubstantially during only the entire duration of possible restrikingwith capacitive interruptions, said braking means including afluid-controlled system having valve means and electromagnetic actuatingmeans for actuating said valve means in response to the current flowingthrough said circuit breaker exceeding a predetermined threshold valueto thereby control the flow of fluid medium within said fluid system,said braking means being operative by admission of said fluid medium.

11. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and the fixed contact fingers ofsaid stationary contact means being disposed on the inside of said oilinjection pot in the closure position thereof, and control means withinsaid oil injection pot for controlling the opening movement of saidmovable contact means including energy storage means armed duringclosure movement of said movable contact means, means including saidenergy storage means for aiding in imlpartin-g at the beginning of theopening movement a very high speed to said movable contact means, andmeans injecting on said movable contact means an anticavitation oilcurrent substantially in the direction of opening movement of saidmovable contact means and during the entire duration of possiblerestrikin with capacitive interruptions including partition Wall meansforming throttling aperture means for the oil and effectively interposedbetween said energy storage means and said spark arrester cover means.

12. A high-voltage, small-oi l-vo lume circuit breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means and including a contact rod, housing meansefiectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and said stationary contactmeans being disposed on the inside of said oil injection pot in theclosure position thereof, and control means Within said oil injectionpot for controlling the opening movement of said movable contact meansincluding energy storage means armed during closure movement of saidmovable contact means and having cylinder means slida-bly accommodatingtherein piston means having a piston rod pushed back by said contact rodduring closing movement thereof to compress spring means,

means including said energy storage means for assisting in imparting atthe beginning of the opening movement a very high speed to said movablecontact means, and means including said piston means for injecting onsaid movable contact means an anti-cavitation oil current substantiallyin the direction of opening movement of said movable contact means andsubstantially only during the entire duration of possible restrikingwith capacitive interruptions.

13. A high-voltage, small-oil-vo lume cirouitabreaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact including a contact rod,housing means effectively forming an oil injection pot and includingspark-arrester cover means, said movable contact means and the fixedcontact fingers of said stationary contact means being disposed on theinside of said oil injection pot in the closure position thereof, andcontrol means within said oil injection pot for control-ling the openingmovement of said movable contact means including energy storage meansarmed during closure movement of said movable contact means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, and means injecting on said movable contact means ananti-cavitation oil current substantially in the direction of movementof said movable contact means during the entire duration of possiblerestriking with capacitive interruptions including partition wall meansforming throttling aperture means for the oil and effectively interposedbetween said energy storage means and said spark arrester cover means,said spark-arrester cover means bein provided with a central bore forthe passage therethrough, with reduced play, of said contact rod andwith perforations for the passage of oil.

14. A high-voltage, small-oi l-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means including a contactrod, housing means effectively forming an oil injection pot andincluding spark-arrester cover means, said movable contact means and thefixed contact fingers of said stationary contact means being disposed onthe inside of said oil injection pot in the closure position thereof,and control means Within said oil injection pot for controlling theopening movement of said movable contact means including energy storagemeans armed during closure movement of said movable contact means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said mo'vab lecont-act means, and means injecting on said movable cont-act means ananti-cavitation oil current substantially in the direction of movementof said movable contact means during the entire duration of possiblerestrikin-g with capacitive interruptions including partition wall meansforming throttling aperture means for the oil and effectively interposedbetween said energy storage means and said spark-arrester cover means,said sparkarrestercover means bein provided with a central bore for thepassage therethrough, with reduced play, of said contact rod and withperforations for the passage of oil, said perforations being in the formof radial channels extending substantially radially outwardly from saidcentral bore.

15. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means including a contactrod, housing means effectively forming an oil injection pot andincluding spark-arrester cover means, said movable contact means and thefixed contact fingers of said stationary contact means being disposed onthe inside of said oil injection pot in the closure position thereof,and control means within said oil injection pot for controlling theopening movement of said movable contact means including energy storagemeans armed during closure movement of said movable contact means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, and means injecting on said movable contact means ananti-cavitation oil current substantially in the direction of movementof said movable contact means during the entire duration of possiblerestriking with capacitive interruptions including partition wall meansformin throttling aperture means for the oil having a divergentdirection in the opening sense of said movable contact means andeffectively interposed between said energy storage means and saidspark-arreste-r cover means, said spark-arrester cover means beingprovided with a central bore for the passage therethrough, with reducedplay, of said contact rod and with perforations for the passage of oil,said perforation-s being in the form of radial channels extendingsubstantially radial- 1y outwardly from said central bore.

16. A high-voltage, sm all-oil-volume circuit-breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means and including a contact rod, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and said stationary contactmeans being disposed on the inside of said oil injection pot in theclosure position thereof, and control means within said oil injectionpot for controlling the opening movement of said movable contact meansincluding energy storage means armed during closure movement of saidmovable contact means and having cylinder means slidably accommodatingtherein piston means having a piston rod pushed back by said contact rodduring closing movement thereof to compress spring means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, brake means for subjecting said movable contact means toa braking action in the opening movement thereof in a position of saidmovable contact means corresponding substantially to optimum positionfor interrupting shortcircuit currents and small inductive currents, andmeans including said piston means for injecting on said movable contactmeans an anti-cavitation oil current substantially in the direction ofdisplacement of said movable contact means during the entire duration ofpossible restriking With capacitive interruptions including throttlingmeans for the oil intermediate the cylinder means of said energy storagemeans and said spark-arrester cover means, said spark-arrester covermeans being provided with per-forations for the passage of oil and saidcontact rod extending through said cover means With a relatively reducedclearance, said perforations being in the form of radial notchesextending radially outwardly from the central aperture provided for thepassage of said contact rod.

17. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means and including a contact rod, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and said stationary contactmeans being disposed on the inside of said oil injection pot in theclosure position thereof, and control means within said oil injectionpot for controlling the opening movement of said movable contact meansincluding energy storage means armed during closure movement of saidmovable contact means and having cylinder means slidably accommodatingtherein piston means having a piston rod pushed back by said contact rodduring closing movement thereof to compress spring means, meansincluding said energy storage means for assisting in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, brake means for subjecting said movable contact means toa braking action in the opening movement thereof in a position of saidmovable contact means corresponding substantially to optimum positionfor interrupting short-circuit currents and small inductive currents,and means including said piston means for injecting on said movablecontact means an anti-cavitation oil current substantially in thedirection of displacement of said movable contact means during theentire duration of possible restriking with capacitive interruptionsincluding throttling means for the oil effectively diverging in theopening direction of said movable contact means and disposedintermediate the cylinder means of said energy storage means and saidspark-arrester cover means, said spark-arrester cover means beingprovided with perforations for the passage of oil and said contact rodextending through said cover means with a relatively reduced clearance,said perforations being in the form of radial notches extending radiallyoutwardly from the central aperture provided for the passage of saidcontact rod.

18. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means, housing means effectively forming an oilinjection pot and including spark arrester cover means, said movablecontact means and said stationary contact means being disposed on theinside of said oil injection pot in the closure position thereof, andcontrol means within said oil injection pot for controlling the openingmovement of said movable contact means including energy storage meansarmed during closure movement of said movable contact means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, and means injecting on said movable contact means ananticavitation oil current approximately in the direction ofdisplacement of said movable contact means and substantially during theentire duration of possible res-triking with capacitive interruptionsincluding cylinder means for the oil, piston means in said cylindermeans having a piston rod with a base, throttling means for the oileffectively formed between said energy storage means and saidsparkarrester cover means, said throttling means being provided withaperture means having effectively a divergence in the direction ofopening movement of said movable contact means, and said injection beingeffected also by said piston which is provided with orificesestablishing a communication for said base with said cylinder means.

19. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means, housing means effectively forming an oilinjection pot and including spark-arrester cover means, said movablecontact means and said stationary contact means being disposed ontheinside of said oil injection pot in the closure position thereof, andcontrol means within said oil injection pot for controlling the openingmovement of said movable contact means including energy storage meansarmed during closure movement of said movable contact means, meansincluding said energy storage means for aiding in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, and means injecting on said movable contact means ananti-cavitation oil current approximately in the direction ofdisplacement of said movable contact means and substantially during theentire duration of possible restriking with capacitive interruptionsincluding partition wall means intermediate said energy storage meansand said sparkarrester cover means forming a perforated diaphragm forthe oil, said partition wall means being axially extended in thedirection of closing movement of said movable contact means by a tubularportion in which stops the head portion of said movable contact means inthe closure position thereof.

20. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means, movable contact means cooperating with saidstationary contact means, housing means effectively forming an oilinjection pot and including spark-arrester cover means, said movablecontact means and said stationary contact means being disposed on theinside of said oil injection pot in the closure position thereof, andcontrol means within said oil injection pot for controlling the openingmovement of said movable contact means including energy storage meansarmed during closure movement of said movable contact means, meansincluding said energy storage means for assisting in imparting at thebeginning of the opening movement a very high speed to said movablecontact means, hydraulically actuated means for subjecting said movablecontact means to braking action in the opening movement thereof in aposition of said movable contact means corresponding substantially tooptimum position for interrupting short-circuit currents and smallinductive currents, and means injecting on said movable contact means ananti-cavitation oil current approximately in the direction ofdisplacement of said movable contact means and substantially during theentire duration of possible restriking with capacitive interruptionsincluding cylinder means for the oil, piston means in said cylindermeans having a piston rod with a base, throttling means for the oileffectively formed between said energy storage means and saidspark-arrester cover means, said throttling means being provided withaperture means having effectively a divergence in the direction ofopening movement of said movable contact means, and said injection beingeffected also by said piston which is provided with orificesestablishing a communication for said base with said cylinder means.

21. A high-voltage, small-oil-volume circuit-breaker comprisingstationary contact means having fixed contact fingers, movable contactmeans cooperating with said stationary contact means, housing meanseffectively forming an oil injection pot and including spark-arrestercover means, said movable contact means and the fixed contact fingers ofsaid stationary contact means being disposed on the inside of said oilinjection pot in the closure position thereof, said oil injection pothaving a reduced diameter in lthe portion thereof directly adjoiningsaid spark-arrester cover means and said fixed contact fingers beingdisposed in said last-mentioned portion, and control means within saidoil injection pot for controlling the opening movement of said movablecontact means including energy storage means armed during closuremovement of said movable contact means, means including said energystorage means for aiding in imparting at the beginning of the openingmovement a very high speed to said movable contact means, and meansinjecting on said movable contact means an anti-cavitation oil currentsubstantially in the direction of displacement of said movable contactmeans during the entire duration of possible restriking with capacitiveinterruptions including throttling aperture means for the oilintermediate said energy storage means and said spark-arrester covermeans.

References Cited by the Examiner UNITED STATES PATENTS 2,459,599 1/ 1949Strom 20015O FOREIGN PATENTS 653,377 11/1937 Germany.

514,704 11/1939 Great Britain. 1,214,863 11/1959 France.

ROBERT K. SCHAEFER, Primary Examiner.

KATHLEEN H. CLAFFY, Examiner.

BERNARD A. GILHEANY, R. S. MACON,

Assistant Examiners.

1. A HIGH-VOLTAGE, SMALL-OIL-VOLUME CIRCUIT-BREAKER COMPRISINGSTATIONARY CONTACT MEANS HAVING FIXED CONTACT FINGERS, MOVABLE CONTACTMEANS COOPERATING WITH SAID STATIONARY CONTACT MEANS, HOUSING MEANSEFFECTIVELY FORMING AN OIL INJECTION POT AND INCLUDING SPARK-ARRESTERCOVER MEANS, SAID MOVABLE CONTACT MEANS AND THE FIXED CONTACT FINGERS OFSAID STATIONARY CONTACT MEANS BEING DISPOSED ON THE INSIDE OF SAID OILINJECTION POT IN THE CLOSING POSITION THEREOF, AND CONTROL MEANS WITHINSAID OIL INJECTION POT FOR CONTROLLING THE OPENING MOVEMENT OF SAIDMOVABLE CONTACT MEANS INCLUDING MEANS FOR AIDING IN IMPARTING AT THEBEGINNING OF THE OPENING MOVEMENT A VERY HIGH SPEED TO SAID MOVABLECONTACT MEANS AND INJECTING ON SAID MOVABLE CONTACT MEANS ANANTI-CAVITATION OIL CURRENT IN THE DIRECTION OF MOVEMENT OF SAID MOVABLECONTACT MEANS SUBSTANTIALLY FREE OF SWIRLING MOVEMENTS DURINGSUBSTANTIALLY THE ENTIRE DURATION OF POSSIBLE RESTRIKING WITH CAPACTIVEINTERRUPTIONS.